Standard Model with right-handed neutrinos

Hey, I would like to ask you: I need have Standard Model with right-handed neutrinos. This is the simplest extension of SM which contains the Dirac and Majorana neutrinos.
PR (right projection operator) coefficients should be nonzero. Is that enough? But what is their value? In the SM for the neutrinos interaction with the Z boson, the coefficients are respectively 1 / 2 and 0.
Do neutrinos further in this model are massless? What is the Lagrangian interaction with W and Z? Is there any name of this model? Are any papers about this model?